The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Vic ambo transfer times a challenge: govt

Victorian Health Minister David Davis admits ambulance ramping and deteriorating hospital transfer times are a "challenge" but money is being spent to ensure a smooth handover of patients.

Mr Davis said the government had invested $151 million in ambulance services, increasing funding by 17.2 per cent, when he was questioned on ambulance response times at a budget estimates committee hearing on Tuesday.

Mr Davis was grilled on performance measures which show the number of ambulance patients transferred within 40 minutes declining from 81.7 per cent to a projected 76 per cent in 2012/13.

"The transfer times are a challenge. We are working on that," Mr Davis said.

He was also interrogated on ambulance ramping, backlogs of grounded ambulances waiting at hospitals to transfer patients.

Mr Davis said the government had invested money to improve data transmission from ambulances to hospitals.

"We understand the importance of having as much of our paramedic workforce vehicles as possible on the road," he said.

"The government has invested $12.9 million to improve handover arrangements and smoothing the arrival of key urgent cases in particular."

Frankston Hospital had one of the lowest ambulance transfer times in the state, with only 58.9 per cent of patients transferred within 40 minutes in the last quarter.

But Mr Davis said the government was responding to the significant challenges Frankston faced in its emergency department.

A 68-bed unit and new emergency department were under construction at Frankston Hospital.